Two mechanisms for poststimulus hyper-polarisations in cultured mammalian neurones

LONG lasting hyperpolarising responses following high frequency spike discharges in neurones from several sub-mammalian species have been attributed to either electrogenic ion transport^1,2 or to a long lasting increase in K⁺ conductance^3,4. These prolonged hyperpolarising responses of whatever mechanism result in alterations of neuronal behaviour which may have important functional consequences for the integrative activity of the central nervous system (CNS). Similar potentials have been reported in studies on the intact mammalian CNS^5-7, but the complexity of these preparations has prevented a thorough analysis. Such phenomena can be studied using intracellular recording techniques in dissociated cell cultures of mammalian neural tissue, and here we demonstrate post-stimulus hyperpolarising responses in cultured spinal neurones and suggest the underlying mechanisms. © 1975 Nature Publishing Group.